@article{li_elhatisari_epelbaum_lee_lu_meissner_2019, title={Galilean invariance restoration on the lattice}, volume={99}, ISSN={["2469-9993"]}, DOI={10.1103/PhysRevC.99.064001}, abstractNote={We consider the breaking of Galilean invariance due to different lattice cutoff effects in moving frames and a nonlocal smearing parameter which is used in the construction of the nuclear lattice interaction. The dispersion relation and neutron-proton scattering phase shifts are used to investigate the Galilean invariance breaking effects and ways to restore it. For $S$-wave channels, ${}^1S_0$ and ${}^3S_1$, we present the neutron-proton scattering phase shifts in moving frames calculated using both L\"uscher's formula and the spherical wall method, as well as the dispersion relation. For the $P$ and $D$ waves, we present the neutron-proton scattering phase shifts in moving frames calculated using the spherical wall method. We find that the Galilean invariance breaking effects stemming from the lattice artifacts partially cancel those caused by the nonlocal smearing parameter. Due to this cancellation, the Galilean invariance breaking effect is small, and the Galilean invariance can be restored by introducing Galilean invariance restoration operators.}, number={6}, journal={PHYSICAL REVIEW C}, author={Li, Ning and Elhatisari, Serdar and Epelbaum, Evgeny and Lee, Dean and Lu, Bingnan and Meissner, Ulf-G}, year={2019}, month={Jun} }
@article{li_elhatisari_epelbaum_lee_lu_meissner_2018, title={Neutron-proton scattering with lattice chiral effective field theory at next-to-next-to-next-to-leading order}, volume={98}, ISSN={["2469-9993"]}, DOI={10.1103/PhysRevC.98.044002}, abstractNote={We present a new lattice formulation of chiral effective field theory interactions with a simpler decomposition into spin channels. With these interactions the process of fitting to the empirical scattering phase shifts is simplified, and the resulting lattice phase shifts are more accurate than in previous studies. We present results for the neutron-proton system up to next-to-next-to-next-to-leading order for lattice spacings of $1.97$, $1.64$, $1.32$, and $0.99~{\rm fm}$. Our results provide a pathway to $\textit{ab initio}$ lattice calculations of nuclear structure, reactions, and thermodynamics with accurate and systematic control over the chiral nucleon-nucleon force.}, number={4}, journal={PHYSICAL REVIEW C}, author={Li, Ning and Elhatisari, Serdar and Epelbaum, Evgeny and Lee, Dean and Lu, Bing-Nan and Meissner, Ulf-G}, year={2018}, month={Oct} }
@article{rokash_pine_elhatisari_lee_epelbaum_krebs_2015, title={Scattering cluster wave functions on the lattice using the adiabatic projection method}, volume={92}, ISSN={["1089-490X"]}, DOI={10.1103/physrevc.92.054612}, abstractNote={The adiabatic projection method is a general framework for studying scattering and reactions on the lattice. It provides a low-energy effective theory for clusters which becomes exact in the limit of large Euclidean projection time. Previous studies have used the adiabatic projection method to extract scattering phase shifts from finite periodic-box energy levels using L\"uschers method. In this paper we demonstrate that scattering observables can be computed directly from asymptotic cluster wave functions. For a variety of examples in one and three spatial dimensions, we extract elastic phase shifts from asymptotic cluster standing waves corresponding to spherical wall boundary conditions. We find that this approach of extracting scattering wave functions from the adiabatic Hamiltonian to be less sensitive to small stochastic and systematic errors as compared with using periodic-box energy levels.}, number={5}, journal={PHYSICAL REVIEW C}, author={Rokash, Alexander and Pine, Michelle and Elhatisari, Serdar and Lee, Dean and Epelbaum, Evgeny and Krebs, Hermann}, year={2015}, month={Nov} }
@article{elhatisari_lee_2014, title={Fermion-dimer scattering using an impurity lattice Monte Carlo approach and the adiabatic projection method}, volume={90}, ISSN={["1089-490X"]}, DOI={10.1103/physrevc.90.064001}, abstractNote={We present lattice Monte Carlo calculations of fermion-dimer scattering in the limit of zero-range interactions using the adiabatic projection method. The adiabatic projection method uses a set of initial cluster states and Euclidean time projection to give a systematically improvable description of the low-lying scattering cluster states in a finite volume. We use L\"uscher's finite-volume relations to determine the s-wave, p-wave, and d-wave phase shifts. For comparison, we also compute exact lattice results using Lanczos iteration and continuum results using the Skorniakov-Ter-Martirosian equation. For our Monte Carlo calculations we use a new lattice algorithm called impurity lattice Monte Carlo. This algorithm can be viewed as a hybrid technique which incorporates elements of both worldline and auxiliary-field Monte Carlo simulations.}, number={6}, journal={PHYSICAL REVIEW C}, author={Elhatisari, Serdar and Lee, Dean}, year={2014}, month={Dec} }
@article{elhatisari_koenig_lee_hammer_2013, title={Causality, universality, and effective field theory for van der Waals interactions}, volume={87}, ISSN={["1094-1622"]}, DOI={10.1103/physreva.87.052705}, abstractNote={We analyze low-energy scattering for arbitrary short-range interactions plus an attractive 1/r^6 tail. We derive the constraints of causality and unitarity and find that the van der Waals length scale dominates over parameters characterizing the short-distance physics of the interaction. This separation of scales suggests a separate universality class for physics characterizing interactions with an attractive 1/r^6 tail. We argue that a similar universality class exists for any attractive potential 1/r^{alpha} for alpha >= 2. We also discuss the extension to multi-channel systems near a magnetic Feshbach resonance. We discuss the implications for effective field theory with attractive singular power law tails.}, number={5}, journal={PHYSICAL REVIEW A}, publisher={American Physical Society}, author={Elhatisari, Serdar and Koenig, Sebastian and Lee, Dean and Hammer, H. -W.}, year={2013}, month={May} }
@article{elhatisari_lee_2012, title={Causality bounds for neutron-proton scattering}, volume={48}, ISSN={["1434-601X"]}, DOI={10.1140/epja/i2012-12110-x}, abstractNote={We consider the constraints of causality and unitarity for the low-energy interactions of protons and neutrons. We derive a general theorem that non-vanishing partial-wave mixing cannot be reproduced with zero-range interactions without violating causality or unitarity. We define and calculate interaction length scales which we call the causal range and the Cauchy-Schwarz range for all spin channels up to J = 3. For some channels we find that these length scales are as large as 5 fm. We investigate the origin of these large lengths and discuss their significance for the choice of momentum cutoff scales in effective field theory and universality in many-body Fermi systems.}, number={8}, journal={EUROPEAN PHYSICAL JOURNAL A}, author={Elhatisari, S. and Lee, D.}, year={2012}, month={Aug} }